U.S. patent number 5,710,467 [Application Number 08/597,223] was granted by the patent office on 1998-01-20 for alternator.
This patent grant is currently assigned to Nippondenso Co., Ltd.. Invention is credited to Hitoshi Irie, Hiroshi Ishida, Shin Kusase.
United States Patent |
5,710,467 |
Irie , et al. |
January 20, 1998 |
Alternator
Abstract
Cooling wind is introduced into an electric-parts-chamber
through openings formed at the bottom of a cover, then taken into
the intake side of a cooling fan through the air intakes formed in
the wall end of a housing from the electric-parts-chamber. The
cooling wind is accelerated by the fan to be driven off from the
outlets formed in the peripheral wall of the housing. The
cylindrical portion of the positive side cooling fins of the
rectifier is extended to the space between the outer periphery of
the fan and the outlets. The inner diameter of the cylindrical
portion is longer than that of the rear coil end. Thus, the coil
end and the cylindrical portion of the positive side cooling fin
are cooled sufficiently by the cooling wind blowing thereon at high
speed, so that the rectifier can endure large thermal load with
reduced wind noise even if the size of the alternator is small.
Inventors: |
Irie; Hitoshi (Nagoya,
JP), Ishida; Hiroshi (Anjo, JP), Kusase;
Shin (Obu, JP) |
Assignee: |
Nippondenso Co., Ltd. (Kariya,
JP)
|
Family
ID: |
26502297 |
Appl.
No.: |
08/597,223 |
Filed: |
February 6, 1996 |
Current U.S.
Class: |
310/64; 310/62;
310/68D |
Current CPC
Class: |
H02K
9/06 (20130101); H02K 11/046 (20130101) |
Current International
Class: |
H02K
9/06 (20060101); H02K 9/04 (20060101); H02K
11/04 (20060101); H02K 001/32 (); H02K 009/00 ();
H02K 011/00 () |
Field of
Search: |
;310/68D,64,62,63
;363/141,145 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0 125 834 |
|
Nov 1984 |
|
EP |
|
60-20748 |
|
Feb 1985 |
|
JP |
|
7-39110 |
|
Feb 1995 |
|
JP |
|
Primary Examiner: Stephan; Steven L.
Assistant Examiner: Wallace, Jr.; Michael
Attorney, Agent or Firm: Cushman, Darby & Cushman IP
Group of Pillsbury, Madison & Sutro LLP
Claims
What is claimed is:
1. An alternator comprising:
a housing having an end wall and a circumferential wall, said
housing having air intakes formed on said end wall thereof and an
air outlet formed on said circumferential wall thereof;
a stator core fixed to said housing and having a stator coil wound
therearound, said stator coil having a coil end protruding axially
from said stator core;
a rotor core supported rotatably by said housing inside said stator
core;
a cooling fan located within said housing, radially inwardly of
said outlet and fixed on said rotor core to generate cooling wind
in a radial direction; and
a rectifier fixed to said housing and having a radiating plate to
cool rectifying elements to rectify AC current generated in said
stator coil into DC current, wherein
said radiating plate of said rectifier has a cylindrical extension
extending axially around said cooling fan, said cylindrical
extension has an inner diameter larger than an inner diameter of
said coil end of said stator coil so that a space is provided
between an outer edge of said cooling fan and said cylindrical
extension, and a space is provided between said coil end of said
stator coil and said cylindrical extension, whereby said cooling
wind blows on said cylindrical extension.
2. An alternator according to claim 1, wherein
a portion of said cooling fan is disposed axially to overlap with
said cylindrical extension; and
said cylindrical extension is located between said cooling fan and
said outlets.
3. An alternator according to claim 1, wherein
a portion of said cooling fan is disposed axially to overlap with
said coil end of said stator coil.
4. An alternator according to claim 1, wherein
a space is provided in a radially inner portion of said rectifier
to allow said cooling wind to pass therethrough.
5. An alternator according to claim 1, wherein
a plurality of openings are provided on said cylindrical extension
of said radiating plate to face said outlets of said housing.
6. An alternator according to claim 1, wherein
said rectifier has a deflecting member for deflecting said cooling
wind axially.
7. An alternator according to claim 6, wherein
a cover is disposed to cover a rear end of said housing; and
outlets for deflected cooling wind are formed on said cover.
8. An alternator according to claim 1, wherein
a cover having a cylindrical portion is disposed to cover a rear
end of said housing;
said rectifier is fixed between said rear end of said housing and
said cover; and
said cylindrical extension of said radiating plate is axially
extended longer than said cylindrical portion of cover.
9. An alternator comprising:
a rotor having a centrifugal fan at one end thereof;
a stator core disposed around said rotor and having an inner
diameter larger than an outer diameter of said centrifugal fan;
a housing having an air intake passage extending from an axially
outside portion of said rotor to a central portion of said
centrifugal fan and an air discharging passage from an outer
periphery of said centrifugal fan to a radially outside portion of
said rotor; and
a rectifier fixed to said housing and having cooling fins and
rectifier elements thermally connected to said cooling fins which
are exposed to said air intake and air discharging passages;
wherein said rectifier has a portion axially spaced from said
centrifugal fan and extending in an arc formed around said air
intake passage to be exposed thereto and a portion disposed
radially outside said centrifugal fan to be exposed to said air
discharging passage.
10. An alternator as claimed in claim 9, wherein said stator
comprises a stator coil which is disposed axially to overlap with
said centrifugal fan, and an outer periphery of said centrifugal
fan extends in parallel with an inner periphery of said stator
coil.
11. An alternator comprising:
a housing having an air intake formed on an end wall thereof and an
air outlet formed on a circumferential wall thereof;
a stator core fixed to said housing and having a stator coil with a
coil end protruding axially from said stator core;
a rotor core supported rotatably by said housing inside said stator
core;
a cooling fan located inside said housing and fixed to said rotor
core to generate cooling wind in a radial direction;
a rectifier fixed to said housing and having a radiating plate,
said radiating plate having a cylindrical extension disposed
between said cooling fan and said air outlet, said cylindrical
extension having an inner diameter larger than an inner diameter of
said coil end of said stator coil to provide a space between said
cooling fan and said cylindrical extension.
12. An alternator according to claim 11, wherein
a portion of said cooling fan is disposed axially to overlap with
said cylindrical extension.
13. An alternator according to claim 12, wherein
a portion of said cooling fan is disposed axially to overlap with
said coil end of said stator coil.
14. An alternator according to claim 11 further comprising a
member, disposed between said cooling fan and said air outlet, for
deflecting cooling window.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cooling system of a rectifier of
an alternator for a vehicle.
2. Description of Related Art
An alternator disclosed in Japanese Patent Laid-Open Publication
No. Sho 60-20748 filed by the same assignee of the present
invention comprises a housing which has air intakes on the bottom
thereof and air outlets on the circumferential wall thereof, stator
coils wound around a stator core fixed in the housing, a rotor core
supported rotatably by the housing inside the stator core, a
cooling fan located under the outlets and fixed on an end surface
of the rotor core to blow the cooling wind in the radial direction,
a dish-shaped cover fixed on the end wall of the housing, and such
electric parts as a rectifier and the like contained in an
electric-parts-chamber formed between the end wall and the cover.
Cooling wind flows from air inlets formed in the bottom of the
cover to the outlets via the electric-parts-chamber, the air
intakes and the cooling fan.
FIG. 5 shows an enlarged view of main parts of a conventional
alternator with a built-in rectifier. A rectifier 200, i.e., a
three-phase full wave rectifier, is contained in a parts-chamber S
between a rear frame 100 and a cover 101. A pipe rivet 103 is fixed
on a bolt 102 inserted horizontally from the end wall of the rear
frame 100. A bush 104, a positive side cooling fin (a radiating
plate) 105, a bush 106, and a negative side cooling fin 107 are
mounted on the pipe rivet 103 in this order. Next, a fixing hole of
the cover 101 is placed on the bolt 102, which is tightened with a
nut 108. Positive rectifying elements (not shown) are fixed in the
positive side cooling fin 105 and negative rectifying elements (not
shown) are fixed in the negative side cooling fin 107,
respectively. These cooling fins 105 and 107 serve as electrode
plates connected to one electrode of respective rectifying
elements.
The above-mentioned structure allows both positive and negative
side cooling fins 105 and 107 to be separated from each other as
well as from the frame 100 and the bolt 102. The pipe rivet 103
serves as a ground electrode of the negative side cooling fin 107
and fixes each bush 104 and 106, and each fin 105 and 107.
In the aforementioned conventional alternator, however, because
electric parts such as the rectifier and the like are disposed at
the intake side of the cooling fan to be cooled by cooling wind
taken in by the fan, wind speed is low and cooling efficiency for
the rectifier which particularly generates more heat than other
electric parts is not sufficient. Thus, operating temperature of
such an alternator becomes high.
Moreover, in some cooling structures as disclosed in EP 0125834 and
U.S. Pat. No. 3,198,972, the cooling wind blows on the radiating
plate of a rectifier. However, in the former one, the distance
between the outer diameter of the cooling fan and the radiating
plate is so short that it causes increased discharge resistance,
lower cooling performance due to reduced amount of the wind, and
louder interfering noise by the wind. On the other hand, in the
latter one, since the radiating plate is formed in the radial
direction, the diameter of its surface area has to be enlarged to
raise cooling performance, which results in a larger-sized
alternator.
Particularly in case the inner peripheral diameter of the radiating
plate is smaller than that of the stator coil end while the inner
peripheral diameter of the stator coil (which tends to affect the
size of an alternator) is not large enough, discharge resistance of
cooling wind to the radiating plate of the heat-generating
rectifier increases. Thus, the radiating plate is difficult to be
cooled and wind noise also becomes louder.
When the inner peripheral diameters of both the radiating plate and
the stator coil end are the same, the wind blowing around the coil
end and the window blowing the radiating plate flow in opposite
directions and collide with each other, resulting in difficulty of
cooling wind discharge and in an adverse effect on cooling
performance.
Since the radiating plate is mostly disposed in a radially limited
range and located discontinuously in the circumferential direction,
not only cooling performance deteriorates but also wind noise
becomes louder if the inner periphery of the radiating plate is
close to the outer periphery of the cooling fan.
The recent trend to manufacture a smaller-sized alternator
generating high output power is apt to worsen the temperature
environment of a rectifier and a stator coil. Under such
situations, there has been an increasing demand to improve cooling
performance as well as noise reduction.
SUMMARY OF THE INVENTION
In light of the above-mentioned problems, the present invention has
been made with its primary object to provide an alternator with
improved cooling performance of the rectifier without increasing
the size of the alternator nor the wind interfering noise.
Another object of the present invention is to provide an alternator
which can take in cooling wind from the outside without reducing
wind volume or increasing intake resistance.
Another object of the present invention is to provide an alternator
with raised raise cooling efficiency effected by forming notches or
holes on the radiating plate to face the outlets, thereby to reduce
the discharge resistance of the cooling wind.
A further object of the present invention is to provide an
alternator which will cool even the radiating plate near the
rectifying element generating heat by deflecting cooling wind.
A further object of the present invention is to provide an
alternator in which an installation place of a rectifier is easily
secured and the radiating plate can be easily cooled with the
cooling wind generated by the fan.
According to the present invention, cooling wind passes around the
inner periphery of the rectifier to go into the intake of the
cooling fan to be accelerated in speed radially and driven from the
outlets on the peripheral wall of the housing.
Particularly in the present invention, a sufficiently large space
is provided between the outer diameter portion of the fan, i.e.,
the discharge side of the cooling fan, and the cylindrical
extension of the radiating plate and the inner diameter of the
stator coil end is shorter than that of the cylindrical extension
of the radiating plate, which enables cooling the radiating plate
efficiently without either increasing the size of the alternator,
reducing the volume of cooling wind blown by the centrifugal fan,
or increasing wind noise. The turbulent flow in the aforementioned
space further improves the cooling performance of the radiating
plate, so that the rectifier can endure a larger thermal load with
assured longer life.
Other objects and features of the invention will appear in course
of the description thereof, which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
Additional objects and advantages of the present invention will be
more readily apparent from the following detailed description of
preferred embodiments thereof when taken together with the
accompanying drawings in which:
FIG. 1 is a sectional view of an alternator for a vehicle according
to the first embodiment of the present invention;
FIG. 2 is an enlarged sectional view of a main portion of the
alternator shown in FIG. 1;
FIG. 3 is a plan view of the rectifier of the alternator shown in
FIG. 1;
FIG. 4 is an enlarged sectional view of a main portion according to
a modified embodiment of the present invention; and
FIG. 5 is an enlarged sectional view of main portion of a
conventional alternator with a built-in rectifier.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An alternator for a vehicle which is a first preferred embodiment
of the present invention is hereinafter described with reference to
FIG. 1. The basic structure of this alternator is as follows. A
frame 1 is composed of a front frame 11 and a rear frame 12, and is
tightened with plural fastening bolts 13. The frame 1 rotatably
supports a rotating shaft 2 on which a Lundell-Rice type field core
31 is fixed. A field coil 32 is wound around the field core 31. The
field core 31 and the field coil 32 compose a rotor.
An armature core 33 is fixed around the field core 31 in the inner
periphery of the frame 1. An armature coil 34 is wound around the
armature core 33. The armature core 33 and the armature coil 34
compose a stator.
A cylindrical cover 4 covers the rear end of the rear frame 12.
Electric-parts-chamber S contains a rectifier 7 which is composed
of a three-phase full-wave bridge of rectifier elements, a brush 8,
and a regulator 9 and is formed between the rear frame 12 and the
cover 4.
When an engine (not shown) drives the rotating shaft 2 by a pulley
21 and the field coil 32 is excited, three-phase AC voltage is
generated in the armature coil 34 and rectified into DC voltage by
the rectifier 7. A mixed flow fan 5 and a centrifugal fan 6 are
installed at the front and the back of the field core 31 carried by
the rotating shaft 2.
A plurality of outlets W' and W are radially disposed in series on
the peripheral walls of the front frame 11 and the rear frame 12
surrounding the centrifugal fan 6, respectively. While the radial
component of the wind generated by the mixed flow fan 5 cools the
front coil end of the stator coil 34, it is blown off from the
outlets W'. On the other hand, the axial flow component of the wind
flows between each pole of the rotor core 31 in the axial direction
and reaches the rear end of the rotor core 31 to be deflected in
the radial direction by the disc portion of the centrifugal fan 6.
It passes through the rear coil end of the stator coil 34 and flows
along the inner periphery and the surfaces of the rear coil end
into an air discharge passage P described below. While cooling the
above-mentioned coil end, the wind is driven off from the outlets
W.
Most of the wind Wi generated by the centrifugal fan 6 passes
through the air discharge passage P between the surface of the rear
coil end of the stator coil 34 and the inner edge surface of the
rear frame 12, then it is driven off from the outlets W in the
radially outward direction.
The main feature of the present invention is hereinafter explained
in detail.
Air intakes 121 are formed in the wall end 120 of the rear frame 12
located at an inner portion by a predetermined distance from the
outer peripheral edge of the rear frame 12. The air intakes 121
extend radially at substantially equal intervals to each other to
introduce cooling wind to the rotor side. The cooling wind Wi blows
from air inlets 40 formed at the bottom of the cover 4 to the inner
periphery of the centrifugal fan 6 via the electric-parts-chamber S
and the air intakes 121. After being accelerated by the centrifugal
fan 6, the cooling wind Wi passes through the air discharge passage
P and is driven off outside through the outlets W on the peripheral
wall of the rear frame 12.
The rectifier 7 as the main feature of the present invention is
hereinafter described with reference to an enlarged sectional view
of the main portions shown in FIG. 2 and a plan view in FIG. 3.
The rectifier 7 is composed of a three-phase full-wave
rectifying-bridge having four positive and negative rectifying
elements 7a and 7b shown in FIG. 3. The negative rectifying
elements 7b include substantially can-shaped positive poles and a
negative terminal protruding from the center of the opposite side
of the can-shaped positive poles, and are press-fitted into holes
bored in a semicircular negative side cooling fin 70. The positive
rectifying elements 7a include can-shaped negative poles and a
positive terminal protruding from the center of the opposite side
of the can-shaped negative poles, and are fixed at the bottom plate
of a substantially semicircular dish-shaped positive side cooling
fin 71. Both cooling fins 70 and 71 function as conductive passages
and radiating plates.
A pipe rivet 73 is fixed on a bolt 72 inserted horizontally from
the end wall of the rear frame 12. A bush 74 made of resin, a
positive side cooling fin (radiating plate) 71, a bush 76 made of
resin, and a negative side cooling fin 70 are mounted on the pipe
rivet 73 in this order. Then, a fixing hole (not shown) formed in
the rear end of the cover 4 is placed on the bolt 72 so that the
cover 4 is tightened by a nut 78. The above-mentioned structure
allows both positive and negative side cooling fins 71 and 70 to be
separated from each other as well as from the rear frame 12 and the
bolt 72. The pipe rivet 73 serves as a ground electrode of the
negative side cooling fin 70 and fixes bushes 74 and 76, and fins
70 and 71.
A cable sheath (protection cover) 77 in the shape of a cylinder
formed integrally with the bush 74 protects and guides a lead wire
34e of the stator coil 34. The cable sheath 77 extends axially from
the bush 74 to the stator coil 34. Particularly in this embodiment,
a cylindrical extension 71a of the positive side cooling fin 71
extends axially to the air discharge passage P between the outer
edge in the diametrical direction of the centrifugal fan 6 and the
outlets W. In other words, a portion of the centrifugal fan 6 is
disposed axially to overlap with the cylindrical extension 71a. A
portion of the centrifugal fan 6 is also disposed axially to
overlap with the rear coil end 34R of the stator coil 34. However,
a predetermined space is provided axially between the edge surface
of the rear coil end 34R of the stator coil 34 and the edge 71b of
the positive side cooling fin 71 facing to the rear coil end 34R,
so that the cooling wind Wi from the centrifugal fan 6 can be
driven off through the outlets W. Furthermore, the inner periphery
of the extension 71a of the positive side cooling fin 71 is located
outside the inner periphery of the rear coil end 34R, so that
sufficient space can be secured between the outer periphery of the
centrifugal fan 6 and the inner periphery of the extension 71a.
More specifically, the inner diameter L1 of the extension 71a of
the cooling fin 71 is designed to be longer than the inner diameter
L2 of the rear coil end 34R by a predetermined length
(L1>L2).
According to the first embodiment, since the cooling wind Wi is
driven by the centrifugal fan 6 and collides with the extension 71a
at a high speed, the extension 71a is cooled sufficiently. The
cooling wind Wi is also designed to flow axially through the space
between the radially inner edge of the rectifier 7 and the radially
outer edge of the brush 8, which is quite different from a
conventional embodiment shown in FIG. 5. That is, since both
cooling fins 70 and 71 are not extended to this space, the
resistance of the air blow can be reduced, and cooling performance
of the rectifier 7 increases especially at the time of low
rotational speed of the fan.
Securing a sufficient space between the positive side cooling fin
71 and the outer diameter portion of the centrifugal fan 6 by
disposing the positive side cooling fin 71 externally can prevent
wind noise from becoming loud, and can generate air turbulence,
which remarkably improves cooling efficiency for the radiating
plates.
FIG. 4 shows a modified embodiment, in which a vane 77a is
integrated with the cylindrical cable protection cover 77 to
deflect the cooling wind instead of extending the cylindrical
extension 71a of the positive side cooling fin 71.
The vane 77a can be formed around the centrifugal fan 6 in the
shape of a ring or a semicircle. The vane 77a is diagonally
disposed between the outer edge in the diametrical direction of the
centrifugal fan 6 and the inner periphery of the circumferential
wall of the rear frame 12 or outlets W and deflects a portion of
the cooling wind Wi generated by the centrifugal fan 6 axially to
the electric-parts-chamber S. The deflected cooling wind is driven
out through a plurality of holes 71b of the positive side cooling
fin 71 and small holes 49 of the cover 4. Accordingly, without
extending the positive side cooling fin 71, cooling efficiency for
the positive side cooling fin 71 can be improved.
As another modified embodiment, a plurality of parallel cuts are
formed axially in the cylindrical extension 71a shown in FIG. 2,
and each parallel piece is twisted by a predetermined angle so that
the wind driven out from the outlets W through the cut spaces
between each parallel piece. The twist angle of the respective
parallel pieces is almost parallel to the flow of the wind driven
by the fan 6 to reduce the pressure loss thereby improving the
cooling efficiency.
Although the present invention has been fully described in
connection with the preferred embodiment thereof with reference to
the accompanying drawings, it is to be noted that various changes
and modifications will become apparent to those skilled in the art.
Such changes and modifications are to be understood as being
included within the scope of the present invention as defined by
the appended claims.
* * * * *